From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BACC1C433FE for ; Sat, 12 Feb 2022 16:38:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237482AbiBLQiE (ORCPT ); Sat, 12 Feb 2022 11:38:04 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:46546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231560AbiBLQiC (ORCPT ); Sat, 12 Feb 2022 11:38:02 -0500 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A3BB212; Sat, 12 Feb 2022 08:37:59 -0800 (PST) Received: by mail-pj1-f46.google.com with SMTP id n19-20020a17090ade9300b001b9892a7bf9so2425062pjv.5; Sat, 12 Feb 2022 08:37:59 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:references:from:in-reply-to :content-transfer-encoding; bh=lWvUkwk07Cqv8ZgRYz64+Y6IpvTasbWoniI+uoJ1w1A=; b=kb+MWWieieJ4S6teqZRTZK/Alw3g9agSrJRupSodtBsPXCxSvvG/m9uA2X6uQIsYAz dXxVxOKs+UPKdTqyqrdS4+VtN7bZ/l42kNwyOSWbIdv0wGiN5LbxwZj5KWEGQpm5jr9Y dYYgc546n3Zw5uHExMPych7JWpbd9YSA7vmx3rAermPM8H/xvYCRleDL6ZJIx0UQEnvD Qqua95Pp9VmPKY2uRLLFd22e04DZkACJ7s2Ah9pGF/3FB3msI2eaVbuJk9qJCPi3VFoL vHxBFY2nt8TrwSdXqS5Gtw//pST0ndSJlLMVNXfz4GvrGZ1aIW8kNMhF1LRdw5KQzt4L IUqg== X-Gm-Message-State: AOAM531ds4FiZd5YpJM6XgC1V3hbPIGhjS/ICDwe+rD/OQWVrKuHa+GT 56Mq4+jg+ysdfJzP2wC+SoU= X-Google-Smtp-Source: ABdhPJyhIL2ILPjKpDpGa5afSF+31xQdglUdqqIFTa4eFiuVp5UuUKZgM5IE7j3FX+AOr1US7QWP6Q== X-Received: by 2002:a17:902:d501:: with SMTP id b1mr6711030plg.120.1644683878329; Sat, 12 Feb 2022 08:37:58 -0800 (PST) Received: from ?IPV6:2601:647:4000:d7:feaa:14ff:fe9d:6dbd? ([2601:647:4000:d7:feaa:14ff:fe9d:6dbd]) by smtp.gmail.com with ESMTPSA id c3sm536994pfd.129.2022.02.12.08.37.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 12 Feb 2022 08:37:57 -0800 (PST) Message-ID: <71d6f14e-46af-cc5a-bc70-af1cdc6de8d5@acm.org> Date: Sat, 12 Feb 2022 08:37:55 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [syzbot] possible deadlock in worker_thread Content-Language: en-US To: Tetsuo Handa , syzbot , jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, syzkaller-bugs@googlegroups.com, Tejun Heo , Lai Jiangshan References: <0000000000005975a605d7aef05e@google.com> <8ea57ddf-a09c-43f2-4285-4dfb908ad967@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/11/22 21:31, Tetsuo Handa wrote: > But this report might be suggesting us that we should consider > deprecating (and eventually getting rid of) system-wide workqueues > (declared in include/linux/workqueue.h), for since flush_workqueue() > synchronously waits for completion, sharing system-wide workqueues > among multiple modules can generate unexpected locking dependency > chain (like this report). I do not agree with deprecating system-wide workqueues. I think that all flush_workqueue(system_long_wq) calls should be reviewed since these are deadlock-prone. Thanks, Bart.